1. Field of the Invention
The present invention relates to a measuring apparatus, such as an oscilloscope and a spectrum analyzer, for measuring a time characteristic and a frequency characteristic of an electrical signal and a frequency-dependent characteristic of an optical component.
2. Description of the Related Art
Generally, in a measurement using a measuring apparatus, such as an oscilloscope and a spectrum analyzer, for measuring a time characteristic and a frequency characteristic of an electrical signal and a frequency-dependent characteristic of an optical component, which apparatus is adapted to show a waveform indication representing a result of a measurement on a screen of a display unit, grids and markers are used in order to accurately know a result of a measurement performed at a certain point.
Grids in the measuring apparatus are lines for dividing an axis of ordinates and/or an axis of abscissas at predetermined intervals so as to facilitate the reading of a waveform that represents a result of a measurement by the reading apparatus and that is indicated on the screen of the display unit.
Further, markers are used for designating arbitrary positions on a waveform representing a result of a measurement, which is shown on the screen of the display unit, and for indicating the values of ordinates and/or abscissas of the positions.
Hitherto, measurement has been performed by indicating the grids and the markers together with a waveform, which represents a result of the measurement, on the screen of a display unit. According to a conventional method of setting a marker thereon, the marker can be moved by using a rotary knob or a cursor key. Moreover, the interval, by which the marker moves by 1 step, can be narrowed or broadened. However, the interval, by which the marker moves by 1 step, cannot be arbitrarily changed at each step.
Furthermore, according to a conventional method of setting the interval between grids, the interval therebetween is determined at a specific value but cannot be set at an arbitrary value.
The conventional methods of setting grids and/or markers cannot be applied to the case that it is continuously determined whether or not the quality of a signal source having an output, in which peak signals appear at predetermined wavelengths, is good, or whether or not the quality of a DUT (Device Under Test) having output spectra, in which absorption spectrum and transmission spectrum occur at predetermined wavelengths, is good, as illustrated in FIG. 1.
In the case that the moving interval of the marker is not equal to the interval between the peaks, as shown in FIG. 1, the conventional methods need to operate the rotary knob or the cursor key at each reading of a peak value to thereby move the marker so that the position of the marker coincides with the position corresponding to the peak value, and thereby compare the position, at which the signal is actually measured, with that, at which the signal originally should appear.